One of the principal mechanisms by which cellular regulation is effected is through the transduction of extracellular signals across the membrane that in turn modulate biochemical pathways within the cell. Protein phosphorylation, orchestrated by enzymes known as kinases, represents one course by which intracellular signals are propagated from molecule to molecule resulting in a cellular response. These signal transduction cascades are highly regulated and often overlapping as evidenced by the existence of many protein kinases as well as phosphatases, which remove phosphate moieties. It is currently believed that a number of disease states and/or disorders are a result of either aberrant activation or functional mutations in the molecular components of kinase cascades. Consequently, considerable attention has been devoted to the characterization of kinases, especially those involved in energy metabolism. One such kinase is glycogen synthase kinase 3.
Two different mammalian isoforms of glycogen synthase kinase 3 have been identified and each is encoded by a separate gene (Shaw et al., Genome, 1998, 41, 720-727; Woodgett, Embo J., 1990, 9, 2431-2438). These isoforms, designated alpha and beta are expressed in different cell types and in different proportions. In some cells, the expression of these isoforms is under developmental control.
Glycogen synthase kinase 3 alpha (also known as Factor A (Woodgett, Embo J., 1990, 9, 2431-2438) and ACLK for ATP citrate lyase kinase (Hughes et al., Biochem. J., 1992, 288, 309-314)) is a serine/threonine protein kinase first described as a factor involved in glycogen synthesis. In this pathway, glycogen synthase kinase 3 phosphorylates select residues of glycogen synthase, the rate-limiting enzyme of glycogen deposition, thereby inactivating the enzyme. Therefore, glycogen synthase kinase 3 plays a predominant role in glycogen metabolism and has consequently been investigated as a potential therapeutic target in disease conditions such as diabetes and insulin regulation disorders (Cross et al., FEBS Lett., 1997, 406, 211-215; Eldar-Finkelman et al., Proc. Natl. Acad. Sci. U. S. A., 1996, 93, 10228-10233; Eldar-Finkelman and Krebs, Proc. Natl. Acad. Sci. U. S. A., 1997, 94, 9660-9664; Eldar-Finkelman et al., Diabetes, 1999, 48, 1662-1666).
Recently, it has been demonstrated that glycogen synthase kinase 3 alpha mediates signal transduction pathways by phosphorylating various cellular proteins (Plyte et al., Biochim. Biophys. Acta., 1992, 1114, 147-162). Included in this group are transcription factors such as Jun family members (Nikolakaki et al., Oncogene, 1993, 8, 833-840), NF-ATc (Beals et al., Science, 1997, 275, 1930-1934), and CREB (Bullock and Habener, Biochemistry, 1998, 37, 3795-3809) as well as proteins involved in apoptotic pathways (Pap and Cooper, J. Biol. Chem., 1998, 273, 19929-19932) and sperm motility (Smith et al., J. Androl., 1999, 20, 47-53; Vijayaraghavan et al., Biol. Reprod., 1996, 54, 709-718).
Currently, there are no known therapeutic agents which effectively inhibit the synthesis of glycogen synthase kinase 3 alpha and to date, investigative strategies aimed at modulating glycogen synthase kinase 3 alpha function have involved the use of antibodies and chemical inhibitors. Disclosed in the PCT publication WO 97/41854 are methods to identify inhibitors of glycogen synthase kinase 3 and the use of these inhibitors for the treatment of bipolar disorders, mania, Alzheimer's disease, diabetes and leukopenia (Klein and Melton, 1997). Other inhibitory compounds are disclosed in WO 99/21859. These heterocyclic compounds are intended for the treatment of a disease mediated by a protein kinase, one of which is glycogen synthase kinase 3 (Cheung et al., 1999). There remains, however, a long felt need for additional agents capable of effectively inhibiting glycogen synthase kinase 3 alpha function. The pharmacological modulation of glycogen synthase kinase 3 alpha activity or expression may therefore be an appropriate point of therapeutic intervention in pathological conditions.
Antisense technology is emerging as an effective means for reducing the expression of specific gene products and may therefore prove to be uniquely useful in a number of therapeutic, diagnostic, and research applications for the modulation of glycogen synthase kinase 3 alpha expression.
The present invention provides compositions and methods for modulating glycogen synthase kinase 3 alpha expression.